/**
 *  Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you under the Apache License, Version 2.0 (the
 *  "License"); you may not use this file except in compliance
 *  with the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing,
 *  software distributed under the License is distributed on an
 *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 *  KIND, either express or implied.  See the License for the
 *  specific language governing permissions and limitations
 *  under the License.
 */
package org.codehaus.groovy.classgen.asm.sc;

import org.codehaus.groovy.ast.ASTNode;
import org.codehaus.groovy.ast.ClassHelper;
import org.codehaus.groovy.ast.ClassNode;
import org.codehaus.groovy.ast.Parameter;
import org.codehaus.groovy.ast.expr.Expression;
import org.codehaus.groovy.ast.expr.VariableExpression;
import org.codehaus.groovy.classgen.asm.StatementMetaTypeChooser;
import org.codehaus.groovy.transform.stc.StaticTypesMarker;

/**
 * A {@link org.codehaus.groovy.classgen.asm.TypeChooser} which reads type information from node metadata
 * generated by the {@link groovy.transform.CompileStatic} annotation.
 *
 * @author Cedric Champeau
 */
public class StaticTypesTypeChooser extends StatementMetaTypeChooser {
    @Override
    public ClassNode resolveType(final Expression exp, final ClassNode current) {
        ASTNode target = exp instanceof VariableExpression ? getTarget((VariableExpression) exp) : exp;
        ClassNode inferredType = (ClassNode) target.getNodeMetaData(StaticTypesMarker.DECLARATION_INFERRED_TYPE);
        if (inferredType == null) {
            inferredType = (ClassNode) target.getNodeMetaData(StaticTypesMarker.INFERRED_TYPE);
            if (inferredType == null && target instanceof VariableExpression && ((VariableExpression) target).getAccessedVariable() instanceof Parameter) {
                target = (Parameter) ((VariableExpression) target).getAccessedVariable();
                inferredType = ((Parameter) target).getOriginType();
            }
        }
        if (inferredType != null) {
            if (ClassHelper.VOID_TYPE == inferredType) {
                // we are in a case of a type inference failure, probably because code was generated
                // it is better to avoid using this
                inferredType = super.resolveType(exp, current);
            }
            return inferredType;
        }
        if (target instanceof VariableExpression && ((VariableExpression) target).isThisExpression()) {
            // AsmClassGenerator may create "this" expressions that the type checker knows nothing about
            return current;
        }
        return super.resolveType(exp, current);
    }

    /**
     * The inferred type, in case of a variable expression, can be set on the accessed variable, so we take it instead
     * of the facade one.
     *
     * @param ve the variable expression for which to return the target expression
     * @return the target variable expression
     */
    private static VariableExpression getTarget(VariableExpression ve) {
        if (ve.getAccessedVariable() == null || ve.getAccessedVariable() == ve || (!(ve.getAccessedVariable() instanceof VariableExpression)))
            return ve;
        return getTarget((VariableExpression) ve.getAccessedVariable());
    }
}
